Science: Helium-Air

The production of helium, a light, rare
gas, has already become a prime requisite for aviation because it is
non-inflammable and saves dirigibles from fire hazard. A new use for
it is likely to be developed as the result of researches by the
Department of the Interior.

Ordinary air is composed of four-fifths nitrogen and one-fifth oxygen
and smaller amounts of other gases such as carbon dioxide. The oxygen
content of air is the only part valuable to man in breathing. When men
work in certain types of caissons, in diving suits or...